Pisces. ] DEVONIAN VERTEBRATA. 587 
narrow, ovate, about three-fourths the depth of the body, their base covered with scales as large as those of 
the tail, but more square; dorsal and anal fins nearly equal, opposite each other, their own length apart; 
they are triangular and pointed, their height exceeding their length; tail diphycercal, of moderate size ; 
attenuated prolongation of the body nearly medial, the caudal fin itself being rhomboidal, pointed in the middle 
retrally ; scales rhomboidal, those of the flanks about two and half lines high, and one and half long, those 
of the tail smaller, more obliquely rhombic, but still with nearly equal sides; all appear under the lens 
minutely and closely punctured, the under side with a strong mesial articular ridge extending about two-thirds 
the length. Total length about fourteen inches ; head about one seventh of the length. 
Its small head and extremely narrow elongate form easily distinguish it from the other species. 
Position and Locality —Old Red sandstone flags of Orkney. 
Explanation of Figures.—Plate 2. C. fig. 1, natural size; 1 a, scale of ditto magnified two diameters, 
shewing the punctured external polished surface; fig. 14, internal surface of scale of ditto, shewing the 
articular ridge. 
DIPLOPTERAX MACROLEPIDOTUS (Sedg. & Murch. Sp.) 
Ref. and Syn. = Dipterus macrolepidotus Sedgwick and Murchison, Geol. Trans. Vol. IIT. t. 16. f. 4 and 5. 
= Diplopterus macrocephalus, Ag. Old Red, t. 16 and 17. 
Dese.—About two feet long, and five inches wide; narrowed abruptly towards the tail; scales irregular, 
thomboidal, loosely attached, about three lines high and two lines long on the flanks; surface very finely 
and closely punctured under the lens. 
Its greater size, particularly of the head, and the loosely attached scattered condition of the scales, distin- 
guish this from the D. Agassizi; there is also less disproportion between the size of the anal fins. 
I find, on examining the original specimens of the Dipterus macrolepidotus, that in size, form, and minute 
punctuation of the surface of the scales, as well as their imperfect connexion with each other, they are 
identical with those subsequently described and figured by M. Agassiz, under the name of D. macrocephalus, 
which latter name therefore becomes a synonym of this species as above. 
Position and Locality—Not uncommon in the black flags of the Old Red sandstone of Caithness. 
Genus. OSTEOLEPIS (Val. and Pent.) 
Gen. Char.—Slender ; first dorsal opposite the space between the ventral and first anal, second dorsal 
opposite the space between the two anal fins; minute tubular puncturing of the scales close and distinct over 
the surface, distinguishing them from those of Palwoniscus; the upper margin of each scale has a narrow 
articular process, which is hid under the inferior border of the scale next above ; teeth very irregular in size. 
OSTEOLEPIS ARENATUS (Ag.) 
Ref —Ag. Poiss. Foss. t. 2 d, fig. 1—4. 
Dese.—V ery elongate, slender, six to nearly seven inches long and one deep; length of the head equalling 
the depth; first dorsal a little behind the middle of the body, small, its length and height equal; second dorsal 
opposite the space between the two anals, larger than the first; caudal rounded; scales one-half higher than 
long, finely granulo-punctate, (the height little more than one line). 
Position and Locality —Not uncommon in the Old Red sandstone of Orkney. 
OsTEOLEPIS BREVIS (M‘Coy). Pl. 2. D. fig. 4. 
Ref—M Coy, Ann. Nat. Hist. 2nd Series, Vol. IT. 
Dese.—Very short, fusiform; length about five inches; body broadest at the anterior part, where the 
width is rather more than one-fourth the length, tapering abruptly to the tail, the pedicle of which is about one- 
